1. Field of the Invention
The present invention relates to a material for sliding members which comprises a composite material of titanium carbide and graphite. More particularly, it relates to a composite material for sliding members which comprises a titanium carbide matrix and a uniform dispersion of graphite in the matrix and which is excellent in self-lubricity and wear resistance.
2. Description of Related Art
Titanium carbide is a ceramic having excellent characteristics such as high strength, high hardness, high melting point, low specific gravity and high electrical conductivity, but is employed only in limited uses for structural materials because of its brittleness. For example, it is used merely as dispersions in cermets or ceramics.
Recently, for obtaining ceramic sintered bodies comprising titanium carbide excellent in mechanical properties as a base, researches have been made on adding various metals, carbides, nitrides or carbon to titanium carbide. Especially, carbon has been being studied as a second phase to be added to titanium carbide because of its self-lubricity based on its molecular structure and compatibility with carbides.
For example, Japanese Patent Kokai (Laid-Open) No. 63-230569 proposes a sintered body comprising titanium carbide and 30% by weight or less of a carbide, a nitride and/or carbon contained as impurities and a method for producing the sintered body. However, the invention of this patent publication has developed titanium carbide as structural materials and it does not require sliding characteristics for titanium carbide. Accordingly, there has been no idea of obtaining materials to be used for sliding members by dispersing graphite in titanium carbide utilizing the above excellent characteristics of titanium carbide.
Furthermore, as materials comprising titanium carbide, "Nippon Seramikkusu Gakujutsu Ronbunshi", 97[5], 1989, pp. 507-12 has proposed a composite material of boron carbide-doped titanium carbide and carbon. However, this literature does not relate to sliding materials. The literature discloses a material comprising titanium carbide in which 5-15% by weight of graphite having a particle size of 3-5 .mu.m is dispersed for improving brittleness of titanium carbide using carbon black. It is clear that since carbon black is used as the raw material, carbon is not uniformly graphitized and even if the composite material is used as materials for sliding members, it is not suitable for that purpose.
As mentioned above, there have been no examples of obtaining materials for sliding members using titanium carbide and utilizing the self-lubricity of graphite.